After signing Anthony Davis to a five-year extension, the 49ers have reportedly started contracts talks with Mike Iupati. (AP)

In speaking with Trent Baalke for a story on left guard Mike Iupati last year, the 49ers general manager stressed the important of having continuity on the offensive line, noting how some of the most storied teams in league history kept their front five largely intact during extended periods of success.

Baalke is clearly hoping to replicate that formula with the Niners, who currently boast one of the league top offensive lines. Of San Francisco’s five starters, three are under contract for at least the next three seasons: right guard Alex Boone (2015), left tackle Joe Staley (2017) and right tackle Anthony Davis (2019).

This morning, the NFL Network’s Albert Breer reported, via Twitter, that the 49ers have started contract talks with Iupati, who is signed through 2014. As discussed here last week, Iupati is a logical candidate for the next extension given his rare skills and the 49ers’ emphasis on power running.

If the 49ers do reach an agreement with Iupati in the near future, they will enter the regular season with four starters on their offensive line signed through at least 2015. In addition, Staley, who will turn 29 in August, will be the only member of that quartet older than 27. The average age of Boone, Davis and Iupati when the season starts: 25.

The lone exception on the line is center Jonathan Goodwin, 34, an 11-year veteran who is signed through 2013. Goodwin could be pushed by recent draft picks Joe Looney and Daniel Kilgore during the offseason, but I’d be shocked if he lost his starting job. A steadying presence who has been termed a “block of granite” by Jim Harbaugh, Goodwin calls out blocking adjustments and has started all 37 games – including playoffs – since arriving in 2011.

Beyond that, of course, there’s something to be said for maintaining continuity on the offensive line.